DRP 393 MPEG-4 Receiver/Decoder
Page 22 (36)
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Rev. L
Decoder video
DRP 393 has extensive VBI processing options. Teletext is extracted from the input transport stream and
inserted in the corresponding lines of the analogue CVBS output signal. The Teletext line in use are
displayed in the Teletext info field.
If a VPS data unit is available in the input data stream this is extracted, evaluated and inserted in line 16 of
the analogue output signal. In this process
all
13 relevant data bytes of the VPS data line are processed.
The current tone status of the output signal is modified according to the selected settings. Thus the
corresponding dual tone identification is inserted in the VPS line at time of the conversion of 2 stereo audio
signals. If no VPS data unit is available in the input data stream a VPS data line is generated internally that
contains the current audio tone status information. In that case the VPS CNI code should also be entered
manually so that the television receiver can correctly display and save the program setting. The configured
CNI code is also inserted in the data line.
The WSS information (Wide Screen Signalling) is extracted from the WSS data unit that is available in the
input data stream. Depending upon the selected aspect ratio this information is modified and inserted in line
23. The video signal is converted to the Letterbox format at a 16:9 anamorphous video transmission and at
a selected aspect ratio of 4:3. The aspect ratio of the video signal available at the CVBS output corresponds
to the identification that is inserted in the WSS line 23.
Video test lines (VITS) specified by CCIR and/or ITU are generated in DRP 393. Thus the standard lines 17,
18, 330 and 331 are inserted in the CVBS signal. Either the standardised CCIR G2 signal for line 331 or
optionally a ramp (for SNR measurements) is inserted in line 331 depending on configuration. Line 329 can
be used in DRP 393 in different ways. Firstly an additional test line “sinx/x” can be entered for group delay
time measurements and secondly this line can also be used for further VPS information if data is available
for this line or if the line can be reserved for the assignment of Teletext.
